Method of centrifugally casting tubular bodies



March14, 1944.. J. BQUCHER 2,344,020

METHOD bF GENTRIFUGALLY CASTING TUBULAR BODIES Filed April 11, 1941Jacques Boucher -mv Patented Mar. 14,

ma'rncm or CENTRIFUGAILY cas'rm mums. nonms Jacques Boncher, PariaFranee; vested in the Alien Property Custodian v Application April 11,1941, Serial No.

In France March 28, 1940 2Claims.

The present invention has for its object to produce by centrifugalmoulding, tubular bodies of metallic or other nature. These bodies areobtained by introducing, in a-suitable'mould, the required quantity ofmaterial in the liquid or plastic state, and by then causing the mouldto rotate on its longitudinal axis at a suitable speed, so that thewhole of the liquid mass is subjected to the action of centrifugal forceand assumes the position of equilibrium resulting. to-

gether from the centrifugal force exerted, from gravity and from thereaction of the mould. The rotary movement, the speed of which can beselected according to an arbitrary law, is then maintained until, by thesubsequent cooling to which it is subjected, thematerial has becomecompletely solid and has assumed sufficient consistency for maintainingby itself the shape previously acquired by centrifugation.

The tubular body. thus obtained can have any outer shape whatever, whichwill be determined solely by the shape which will have been initiallychosen for the mould.

The inner shape of the tubular body will be determined bycentrifugation. This. shape will therefore be a body of revolution aboutthe axis of rotation of the mould. Said shape will be cylindrical in thecase in which the axis of rotation is maintained in a horizontalposition, and the diameter of the cylindrical axial space can be freelydetermined by charging the volume of liquidmaterial cast inconsideration of the useful volume of the mould adopted. The inner shapeof the tubular body will be that of a paraboloid in the case in whichthe axis of rotation of the mould is maintained in an inclined positionand the parameters of the central space thus created will depend both onthe volume of material cast in the useful capacity of the mould, on theangle of inclination of the axis of rotation of the mould relatively tothe horizontal and on the speed of walls or end walls made ofmetalcoated or covered with insulating or refractory material, one

(or 22-200). a

,According to the invention. at any moment during the operation, themould can be caused to.

pivotaccording to. an arbitrary law, so as to cause the axis of rotationto assume a position more or. less inclined on either side of thehorizontal and, the final inclination which it is desired to give totheaxis of rotation of the mould can be determined, at every instant.According to another feature of the invention. the introduction of'themetal into the mould is effected by projecting the liquid material inthe 1 form of a jet which freely penetrates through an orifice providedfor that purpose in one of the end walls of the mould. The devicevproducing the casting jet accompanies the mould in all its movements ofinclination. and the casting can be effected as well with the mould inan inclined positionas with the mould in a horizontal position.

The inlet orifice can .be arranged according to the axis of rotation ofthe mould. As its position thusremains fixed during the rotation ofmould, it is very easy to eifect the casting as well when the mould isrotating as when it is at rest.

the most favourable physico-chemical constitu-' tion of the masses ofmaterials constituting the moulded member.

It is possible to act in the most eilicient mane her in the cooling towhich the cast mass is sub-- 40 jected externally by conductabilitythrough the wall of the mould and by radiation at the free surface ofthe latter: Y 1. The mould can, in fact, be constituted by v a bodywhich is a more or less good conductor-of heatand has a more or lessactive radiating surface. Ifdesired, the mould can alsobe cooledartiflcially at the outside by convection in asuit-- able'fiuid. Themould can also act by its relative volume, more or less large, thatis'tn say by the thermal inertia represented by'the calorific capacityof said volume, and said thermal inertia canbemodifiedatwillbytheinitial temperature imparted to the mould before casting.

2. On the contrary, if desired. the mould can of said end walls beingprovided with an orifice be internally lined with a moreo'r less thicklayer of insulating or refractory material which allows of retarding asmuch as desired the cooling effect exerted by the mould and through theresult sought for, these thermal influences can be caused to varyarbitrarily. throughout the extent of the mould, so asto produce anydifferential law of cooling at the outer surface of" the moulded member.

The cooling to which the cast mass can besubjected at its free internalsurface can also be actively acted upon. As soon as centrifugation hasproduced the internal cylindrical or paraboloidal space, an adjustablecooling action can immediately be exerted in the internal space thuscreated, for instance by causing a fluid to circulate which penetratesthrough the casting orifice andv escapes through the vents provided in,

the opposite end wall. If it is desired to exert a reheating action forslackening-or preventing the cooling effect through the internal freesurface, use can be made of a flame which is more or less hot, or moreor less reducing or oxidizing. It is moreover possible, by utilising aflat and hermetically closed end wall at the end opposite the castingend, to preventany natural renewal of the air contained in thecentralfspace and consequently, to practically annui the cooling of thematerial through its internal free surface. The interfering coolingeflect imputable to the presence of the casting orifice can itself beeliminated, by suitably reheating. On the other hand, the process allowsof reducing said interfering effect to the minimum, owing to the verymethod of introducing the liquid material in the form of a jet ofreduced cross section which allows of diminishing the cross section ofthe orifice to .the strict minimum. Furthermore, if the casting iseifected in the mould arranged, for instance, in an inclined positlon,it is possible, during or after casting, to bring the'mould to thehorizontal or even beyond the horizontal position and into an oppositeinclination by.a suitable tilting movement, which has the effect ofcausing the liquidmaterial to fiow towards the casting orifice and toproduce a disc-like portion of material. which rapidly solidifies infront of the casting orifice which is thus automatically obturated, thesolidification than continuing in a hermetically closed vessel and thecooling taking place onlytthrough-the walls of the mould.

By effecting this tilting movement of the mould at the right moment witha suitable amplitude and at suitable intervals of time. and by suitablyconformingthe ends of the mould, a judicious cooling action can beeasily exerted through the end walls, and tubular bodies can be obtainedwhich are closed by end walls integral with the tubular portion and theshape and thickness of which can be easily controlled. Thus, accordingto the invention, it is possible to produce tubular bodies closed at theends and the central space of which will be completely or partly ofcylindriof the member at its ends.

It will be noted that, forthe manufacture of relatively short tubularmembers, it will be advantageous to obtain, according to the invention,long tubular bodies which will then be sectioned into elementarylengths.

o Other features of the invention will be apparent from the followingdescription.

The accompanying drawing diagrammatically shows, and by way of example,a plant for carrying the invention into practice.

In this example, given simply by way of illustration, the mould l which,in this case,- is assumed to be cylindrical, is provided with an upperend wall 2 and a lower end wall 3, the upper end wall being providedwith an orifice lvfor introducing the liquid material This orifice is ofreduced cross section and can have for instance a diametercomprisedbetween 30 and 70 m. m. The mould can, for instance, assume aninclined position at the moment of casting. It rests on sets of drivingrollers 6 and -'I carried by shafts 8. The rollers I roll incontactwith-an abutment 9 provided on the mould for preventing the mould fromsliding downwardly during, the rotation. Each of the shafts 8 is carriedby bearings 26 III which rest 'on a frame I I. Said frame pivots at I2on a supporting beam, not shown, and it can be tilted about said pivot,for instance by a hydraulic jack l3. The frame If carriesanengine whichdrives the shaft 8 for instancebye.

pulley l5. .Said frame moreover carries a casting pot It terminating atthe bottom by anose or nozzle I! which can be brought opposite and nearthe casting orifice 4. The liquid material .is brought to the castingpot it for instance by as a ladle provided with a stopper-rod, notshown.

The height of the casting pot is calculated so as to impart a suitablemomentum to the casting jet. The quantity of liquid material to beintro-,y duced is determined according to the thickness 40 and the calibre ofthe tubular member to be obtained. The liquid material'is poured intothe mould throughthe nozzle I! in the form of a liquid jet which freelyenters through the orifice l. The mould being set in rotation (at anadjustable speed) the. cast material is thus projected by centrifugationagainst the wall of the -mould and, aftercomplete solidification, acentrifugated tubular body is finally Obtained. If it is desired toobtain a perfectly cylindrical internal space, the mould wm be broughtto a horizontal position as soon as the casting is finished. If themould remains in any inclined position, the'internal space willof-course be in the shape of a paraboloid. If the cooling of the liquidmass has been suitably conducted, the wall of the tubularbody obtained,will be perfectly compact and well constituted physically.

The invention is not limited to the embodiments illustrated anddescribed which have been. chosen simply by way of example.

Having now described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A method for the centrifugal casting of tubular bodies with two solidclosed ends in a mould adapted topivot round a horizontal axis,consisting in pouring molten metal into the mould, rotatinglatter athigh speed for the production of the tubular body, tilting the mouldinto a position substantially at an angle with the'horimntal with theinlet end of the mould at a higher level than the opposite end during afraction of the time required for the production of said tubular bodyfor forming a solid closure for the tubular body at said opposite end ofthe mould, simultaneously cooling. said opposite end, tilting the terrapidly, tilting the mold into an inclined position with the inlet endraised for a portion 0! the time required for cooling the body in orderto form a solid-end closure at the opposite end of the mold and tiltingthe mold into an oppositely inclined position and cooling the loweredinlet end in order to form a solid closure for the second end of thetubular body.

JACQUES BOUCHER.

